1. Technical Field
The present invention relates to a liquid crystal display, and more particularly to an LCD having a wide viewing angle.
2. Description of the Related Art
A liquid crystal display (LCD), which is one of the most widely used flat panel displays, typically includes two substrates having field-generating electrodes thereon and a liquid crystal (LC) layer interposed between the two substrates. To produce an image on the LCD, voltage signals are applied to the field-generating electrodes of the substrates to generate an electric field across the LC layer and thus control the orientation of LC molecules of the LC layer. The controlled orientation of the LC molecules creates an image by adjusting the polarization of incident light.
In comparison with conventional cathode ray tube (CRT) displays, an LCD has a narrower viewing angle. A number of techniques have been proposed to overcome this drawback, one of the techniques being known as Vertically Aligned (VA) mode LCD. In the VA mode LCD, the liquid crystals are vertically aligned to the substrate surface plane at the off-state where no voltage or off-voltage is applied, so that the incident light leakage through the LCD is almost zero in the black state (off state with Cross-Nicole state). Due to this minimized light leakage, the Contrast Ratio (CR) of the VA mode LCD, which represents the ratio of white state luminance to black state luminance, is higher than that of any other mode LCDs, such as Twisted-Nematic (TN) mode LCD and In-Plane-Switching (IPS) mode LCD, which employs another enhanced viewing angle technique.
As described above, the VA mode LCD provides an improved viewing angle from the standpoint of Contrast Ratio. However, in the VA mode LCD, like other mode LCDs, the color patterns viewed from the vertical direction to the LCD and from the slanted direction are recognized somewhat differently. This phenomenon (“Color Shift”) comes from the fact that the light path changes depending on the viewing angle. Accordingly, the voltage-transmittance curve (the V-T curve) or the gamma curve also change relative to the viewing angle.